Thread

The engineering behind the US Strategic Petroleum Reserve

281 points · 115 comments · johnjwang

kulahan · 1789604805 · focus · HN ↗
I’m certain engineers have considered this, but it doesn’t seem answered anywhere: why not just pump the original brine back in to move around the oil? Wouldn’t that at least prevent eroding the storage unit and causing it to fail?
Unrelated: dang, he wasn’t underselling this being a pretty elegant solution! I never would’ve thought of it, for sure.
1. aesthesia · 1789605415 · focus · HN ↗
  Wouldn't you then need to solve the similar problem of where to store the brine in the meantime?
  1. kulahan · 1789611876 · focus · HN ↗
    Yeah, but that’s probably easier to solve than eventually losing the whole dang structure!
    rtkwe · 1789668570 · focus · HN ↗
    Depends a lot on how quickly it erodes the salt dome and the costs of using and storing the brine instead of using fresh water. Storing that much brine runs into the same space issues that storing the oil above ground would, slight ameliorated by the brine at least not being flammable.
    rtkwe · 1789751003 · focus · HN ↗
    Looking broadly at the costs to use brine instead of fresh water you'd need a combo of stored brine and a method to generate brine from freshwater (for withdrawals) and then desalinate the brine (for deposits). And that would require quite a bit of infrastructure to store and process the salt generated and used by the freshwater <-> brine process in both directions. Depending on how quickly you want to be able to draw down the SPR you'd need to store a significant amount of salt at the location.
    At a maximum to be able to withdraw the entire reserve you'd need 1.3561 × 10^7 cubic meters of halite (this number uses the density of halite as a solid crystal not the density of a pile of ground up halite they'd actually use) weighing 2.94273 × 10^10 kg or 29.4273 Tg (teragrams, a rare treat to get to break out that unit). [0] That number gets smaller when you allow for receiving shipments of salt during the drawdown since they can't instantly pull out the full reserve so they have time to allow for receiving salt shipments.
    [0] <a href="https://www.wolframalpha.com/input?i=%28714+million+barrels+of+water+weight%29+*+.26+%2F+density+of+halite&assumption=%22UnitClash%22+-%3E+%7B%22barrels%22%2C+%7B%22BarrelsOfOil%22%7D%7D" rel="nofollow">https://www.wolframalpha.com/input?i=%28714+million+barrels+...
2. samus · 1789628586 · focus · HN ↗
  Yes, that's what they do. The brine is stored in huge pools next to the extraction site.

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